Electrical surge arrester



July 10, 1951 L. L. CRUMP H Al. 2,559,599

ELECTRICAL SURGE ARRES'IER Filed June 7, 1947 I l l I FIG. 2

INVENTOR5 LINDELL LLOYD CRUMP CHARLES Aom Fox ATTO RN EY Patented July10, 1951 ELECTRICAL SURGE ARRESTER Lindeil Lloyd Crump,

Fox,

poration of Missouri Kirkwood, and Charles Adin Oakland Village, Mo.,assignors to James R. Kearney Corporation,

St. Louis, Mo., a cor- Applieatlon June 7, 1947, Serial No. 753,314 5Claims. 17 -30) This invention relates generally to electricalprotective devices which are adapted for use in protecting electricalcircuits and the equipment associated therewith from the damagingefiects of surges resulting from lightning and other causes, thepredominant object of the invention being to provide an electricalprotective device of this type which includes spaced elements thatprovidefian air gap, and which is of such improved construction andarrangement that heavy surges will not permanently disturb the settingof the air gap.

Prior to this invention, surge arresters of the general type of the onedisclosed herein have been employed which were provided each with an airgap produced by spaced elements that were fixedly secured in theirrelated positions to provide the air gap. In the use of these earliersurge arresters it has been found that when an arc was formed across theair gap by a heavy surge, there was a tendency for one of the elementswhich produced the air gap to be permanently bent, or otherwisedisplaced from its normal gap-producing position, so that the width ofthe air gap was permanently increased with each action of the surgearrester with the result that the surge arrester was eventually renderedinefiective for the purpose for which it was installed.

The surge arrester of the present invention is of such improvedconstruction and arrangemen that the difliculties recited above areeliminated in the foperation of the surge arrester, this re sult beingattained by mounting one of the gap producing elements of the surgearrester for such movement that the air gap may be increased on passagethereacross of a heavy surge and so that saidmovabiy mounted elementwill return to its normal position after the surge has passed. Thus,while the passage across the air gap of the surge arrester of a heavysurge may increase the width of said air gap momentarily during suchpassage of the heavy surge, the width of the air gap is not permanentlyaltered, as was frequently the case heretofore, but, instead, themovably mounted gap-producing element returns to its normal positionafter being moved by a heavy surge so as to provide an air gap of theproper setting for efliciently by-passing subsequent surges which areimposed on the circuit protected by the surge arrester.

Fig. 1 is a front elevation of the improved surge arrester of thepresent invention.

Fig. 2 is a view partly in side elevation and partLvin vertical sectionof the surge arrester illustrated in Fig. 1.

' contacts with the lower face of In the drawing wherein is shown forpurposes of illustration, merely, one embodiment of the invention, Adesignates the improved surge arrester generally. The surge arrester Aincludes as a part of its structure an insulator I, preferably,thoughnot necessarily, of the petticoat type, said insulator havingformed therethrough from end to end thereof an opening 2.- Mounted atthe upper end of the insulator I is a head member 3 which is formed from'metal, or other material which is a good conductor of electricalenergy, said head member being illustrated as having a curved top and asbeing provided with an annular flange 4 from which is extendeddownwardly a portion 5 whose bottom face contacts with the top face ofthe insulator" I. At the lower end of the insulator I a groundterminal 6is provided, this ground terminal being formed from metal, or otherelectrical conductive material. The ground terminal 5 comprises a lowertapered portion 1, an annular flange portion 8, and a portion 9 whichextends upwardly from said flange portion and whose top face theinsulator I. The portion 9 and the flange portion 8 of the groundterminal 6 have formed centrally therethrough a screwthreaded openingI", and this opening I0 communicates with a vent opening II which isopen at the front of the tapered portion I of the ground terminal 6.

Disposed within the opening 2 of the insulator I and projected beyondthe opposite ends thereof is a tubular element I2 which is formed ofhorn fiber, or other material which is characterized by the ability togive oif gas in the presence of the heat of an electrical are whichtends to extinguish the arc. The tubular element I2 is externallyscrewthreaded at its upper end, as is shown in Fig. 2, and thisscrewthreaded upper portion of said tubular element is screwed into ascrewthreaded opening I3 which is formed in the head portion 3.Likewise, the lower portion of the tubular element I2 is externallyscrewthreaded and this lower, screwthreaded portion of said tubularelement is screwed into the screwthreaded opening III of the groundterminal I so that the vent opening II of said ground terminalcommunicates with the interior of the tubular element I2, as is shown inFig. 2. From the foregoing it is obvious that the insulator I. the headmember 3, and the ground terminal I are held in their assembled relationby the tubular element I2.

Disposed within the tubular element I 2 is an electrode II which isprovided with an externallv screwthreaded upper end portion that isscrewed assasee into a screwthreaded opening it formed in the headmember 3. The electrode it extends downwardly from its point ofattachment to the head member 3 to a point spaced upwardly from theground terminal '3 so as to provide a gap it within the tubular elementi2 and between the lower end of the electrode I4 and the ground terminal5.

Supported by the insulator I is a pair of members I1 and I8, the memberI1 being disposed at the front of the insulator while the member II islocated at the rear of said insulator. The members I1 and I! are fixedto the insulator I by elongated rods I9 which are: arranged at oppositesides of the insulator, said rods at their opposite ends being extendedthrough socket elements formed on the members I1 and I8, and nuts 2|being mounted on the screwthreaded end portions of said rods andcontacting with faces of said socket elements so as to draw the membersl1 and I8 toward each other and securely clamp said members to theinsulator I.

The member I1 is shaped in side elevation as is shown in Fig. 2 andsecured to said member II by means of a pivot pin 22 for pivotalswinging movement is an arm 23, said pivot pin being extended throughopenings formed through portions of said member I1 and portions of thelower part of the arm 23. The upper portion of the arm 23 is curvedinwardly, as indicated at 24 in Fig. 2,'and the inner end of saidinwardly curved upper end portion of said arm 23 is spaced from anadjacent portion of the annular flange 4 of the head member 3 to providean air gap 25 between said parts. The pivot pin 22 which supports thearm 23 has arranged thereabout a torsional coil spring 26 whose oppositeend portions respectively engage a portion of the arm 23 and a portionof the member I'I whereby said torsional coil spring tends to maintainthe arm 23 in the position in which it is shown by full lines in Fig. 2.Also, the arm 23 has formed therethrough a screwthreaded opening throughwhich is screwthreadedly extended the shank of a headed adjusting bolt21, the end of said bolt shank remote from the head of the bolt abuttingagainst an upwardly projected extension I1 formed on the member I1. Thebolt 21 serve as a stop element which maintains the setting of the gap25, and also said bolt may be adlusted, in an obvious manner, so as toincrease or decrease the width of said gap 25.

The member I8 is provided with a, portion I8 to which a line wire L ismechanically and electrically secured by means of a suitable connector20. Likewise, the ground terminal I is provided with an extension I towhich is mechanicall and electrically connected, with the aid of asditable connector 29, a ground wire G. The insulator I has attachedthereto a suitable hanger which serves as means for mounting the surgearrester A on a cross arm, or other support.

In the operation of the improved surge arrester disclosed herein thepath of the surge current is by way of the line wire L to the member I8and across to the member II by way of the rods I8 to and through the arm23 and across the air gap 25 to the head member 3. From the head member3 the surge current moves downwardly of the electrode I4 and across theinternal gap I8 within the fiber tube I2 to the ground terminal I. Thecurrent passing along the arm 23 in one direction and along theelectrode I in the opposite direction sets up opposing magnetic fieldswhich tend to move the arm 23 outwardly to an outwardly displacedposition. as indicated by dotted lines in Fig. 2. Thn action increasesthe width of the gap 25; and assists in extinguishing the areplayingacross said gap, and after the surge has passed the torsionalcoil spring '28 returns the arm 23 to its normal'setting, as shown byfull lines in Fig. 2. The prime function of the air gap 25 is to keeppotential ofl of the surge arrester under normal conditions, while thefunction of the internal gap is is to extinguish the are createdthereacross under surge conditions by subjecting said are to thearc-extinguishing efiect of gas given oif by the horn fiber tubularelement I2 in the presence of the heat or the arc.

From the foregoing it is plain that the pivotally supported arm 23 ofthe surge arrester A may adjust itself in response to electrical forceset up by passage of surge current through the surge arrester toincrease the width of the air gap 25. and will return to its originalposition to reestablish the original setting of said air gap after thesurge has passed. Thus, there is no permanent altering oi the width ofthe air gap 25 as a result of passage of surge current thereacross.

as was frequently the case heretofore when an arm corresponding to thearm 22 was mounted in a fixed position with respect toa membercorresponding to the head member 3.-

We claim:

1. An electrical surge arrester comprising a hollow insulator, a memberformed of electrical conductive material supported by said insulator atan end thereof,'a structure supported by said insulator and providedwith means for connectmg a line wire to said structure, an arm movablysupported by said structure and having a portion thereof spaced from aportion of said member to provide an external air gap therebetween, asecond member formed of electrical conductive material which issupported by said insulator in spaced relation with respect to thefirst-mentioned member at the opposite end thereof, means for connectinga ground wire to said second memher, and an electrode connected to thefirst-mentioned member and disposed within said insulator in a manner toprovide an internal arc gap within said insulator between a portion ofsaid electrode and said second member, said arm and said electrode beingso arranged in the surge arrester structure that current passes alongthe arm in one direction and along the electrode in the oppositedirection whereby opposing magnetic fields are set up which tend to movethe arm to an outwardly displaced position with respect to said memberso as to increase the gap between said arm and said member.

2. An electrical surge arrester comprising a hollow insulator, a memberformed of electrical conductive material supported by said insulator atan end thereof, a structure supported by said insulator and providedwith means for connecting a line wire to said structure. an armpivotally supported by said structure and having a portion thereofspaced from a portion of said member to provide an external air gaptherebetween, a second member formed of electrical conductive materialwhich is supported by said insulator in spaced relation with respect tothe first-mentioned member at the opposite end thereof, means forconnecting a ground wire to said second mem-- ber, and an electrodeconnected to the first-men tioned member and disposed within said insulater in a manner to.provide an internal arc gap within said insulatorbetween a portion of saidelectrode and said second member, said arm andit said electrode being so arranged in the surge arrester structure thatcurrent passes along the arm in one direction and along the electrode inthe opposite direction whereby opposing magnetic fields are set up whichtend to move the arm tr. an outwardly displaced position with respect tosaid member so as to increase the gap between said arm and said member.

3. An electrical surge arrester comprising a hollow insulator, a memberformed of electrical conductive material supported by said insulator atan end thereof, a structure supported by said insulator and providedwith means for connecting a line wire to said structure, an armpivotally supported by said structure and having a portion thereofspaced from a portion of said member to provide an external air gaptherebetween, spring meansfor returning said pivotally supported arm toits normal position when it has been moved from said normal position, asecond member formed of electrical conductive material which issupported by said insulator in spaced relation with respect to thefirst-mentioned member at the opposite end thereof, means for connectinga ground wire to said second member, and an electrode connected to thefirst mentioned member and disposed within said insulator in a manner toprovide an internal arc gap within said insulator between a portion ofsaid electrode and said second member, said arm and said electrode beingso arranged in the surge arrester structure that current passes alongthe arm in one direction and along the electrode in the oppositedirection whereby opposing magnetic fields are set up which tend to movethe arm to an outwardly displaced position with respect ,to said membersoas to increase the gap between said arm and said member.

4. An electrical surge arrester comprising a hollow insulator, a memberformed of electrical conductive material supported by said insulator atan end thereof, a structure supported by said insulator and providedwith means for connecting a line wire to said structure, an armpivotally supported by said structure and having a portion thereofspaced from a portion of said member to provide an external air gaptherebetween, torsional spring means for returning said pivotallysupported arm to its normal position when it has been moved from saidnormal position, a second member formed of electrical conductivematerial which is supported by said insulator in spaced relation withrespect to the first-mentioned mem- Ber at the opposite end thereof,means for connecting a ground wire to said second member, and anelectrode connected to the first-mentioned member and disposed withinsaid insulator in a manner to provide an internal arc gap within saidinsulator between a portion of said electrode and said second member,said arm and said electrode tion and along the electrode in tne oppositedirection whereby opposing magnetic fields are set up which tend to movethe arm to an outwardly displaced position with respect to said memberso as to increase the gap between said arm and said member.

5. An electrical surge arrester comprising a hollow insulator, a memberformed of electrical conductive material supported by said insulator atan end thereof, a structure supported by said insulator and providedwith means for connecting a line wire to said structure, an armpivotally supported by said structure and having a portion thereofspaced from a portion of said member to provide an external air gaptherebetween, means for returning said pivotally supported arm to itsnormal position when it has been moved from said normal position,adjustable means comprising a screwthreaded element supported by saidarm and adapted to abut against a part of said structure forestablishing and maintaining the normal position of said arm, a secondmember formed of electrical conductive material which is supported bysaid insulator in spaced relation with respect to the first-mentionedmember at the opposite end thereof, means for connecting a ground wireto said second member, and an electrode connected to the first-mentionedmember and disposed within said insulator in a manner to provide aninternal arc gap within said insulator between a portion of saidelectrode and said second member, said arm and said electrode being soarranged in the surge arrester structure that current passes along thearm in one directhat current passes along the arm in one direction andalong the electrode in the opposite direction whereby opposing magneticfields are set up which tend to move the arm to an outwardly displacedposition with respect to said member so as to increase the gap betweensaid arm and said member.

LINDELL LLOYD CRUMP.

CHARLES ADIN FOX.

4 REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,197,485 Heinritz Sept. 5, 19162,108,465 Austin Feb. 15, 1938 2,169,110 Pittman Aug. 8, 1939 2,177,744Pittman Oct. 31, 1939 2,296,621 Wade Sept. 22. 1942 2,338,479 AckermannJan. 4, 1944 2,427,460 Johnson Sept. 16, 1947 FOREIGN PATENTS NumberCountry Date 543,571 Great Britain Mar. 4, 1942

